Refrigerator control system



Ange L'l i i Y J N. ROTH I 235497@5 I REFRIGERATOR CONTROL SYSTEM Filed June 27. 1941 :2 Shams-Sheet 1 Au .1,1944. J. N. ROTH 2,354,705

REFRIGERATOR CONTROL SYSTEM Filed auriez'r, 1941 s Sheets-Sheet 2 E III! A! Aug, 3, 1944. J. ROTH I 2,354,705 I REFRIGERATOR CONTROL SYSTEM Filed June 27, 1941 3 Sheets-Sheet a IVEEATOR P/PfSSl/HE A FUR/4 7 0:?

GENERATOR PRESSURE EI/APO/FATOR TEMP.

Patented Aug. 1, 1944 UNITED STATES REFRIGERATOR CONTROL SYSTEM Joseph N.

mesne assignments, Company, Greenville,

Michigan Roth, Beld nl, Mich, assignor, by Q to Gibson Refrigerator Micln, a corporation of Application June 27, 1941, Serial No. 409,039

9 Claims. (cits-) This invention relates to a refrigerator control system, and more particularly to means for controlling the delivery of refrigerant from a high pressure portion to a low pressure portion of a refrigeration system.

One feature of this invention is that it provides improved means for controlling delivery of liquefied refrigerant from the condenser to the evaporator of a continuous absorption refrigeration system; another feature of this invention is that it provides for complete stoppage of refrig-' erant flow to the evaporator at desired periods; another feature of this invention is that it obviates the need of a flow controlled or other type of expansion valve assuming partially open positions and liable to wire drawing and similar difiiculties; a further feature of this invention is that it is particularly adapted for use in a continuous absorption refrigeration system of the type using a transfer chamber to return liquor from the absorber to the still, and where transfer action is controlled by balancing still pressure against another force; other features and advantages of this invention will be apparent from the following specification and the drawings, in which:

Figure 1 is a schematic or diagrammatic showing of a system employing this invention as em- 1 bodied in a domestic continuous absorption refrigerator; Figure 2 is a detail view, principally in vertical section, of the capillary tube portion of the system; Figure 3;. is a top plan view of the valve unit; Figure 4*is a detail view, principally in cross section, of the valve'unit, along the line l-J of Figure 3; Figure 5 is fragmentary transverse sectional view along the line 5-5 of Figure 3; Figure 6 is a chart of still pressure in apparatus not incorporating my invention; Figure 7 is a chart showing evaporator temperature in the same apparatus; Figure 8 is a chart showing still pressure in the same apparatus where my invention is used; and Figure 9 is a chart showing evaporator temperature in the apparatus of Figure 8.

In the particular embodiment of my invention described herewith, the system in general comprises a still adapted to have a mixture of refrigerant and absorbent, as ammonia and water,

boiled therein by the application of heat; a condenser connected by a vapor conduit-to the still to liquei'y the refrigerant vapor delivered there-- by: an evaporator or cooling unit in which the liquefied refrigerant is permitted to vaporize, the evaporator having restricted connection wittnthe the evaporator is reabsorbed in liquid; and means for eflecting flow of weak liquor from the bottom of the still to the absorber and fiow of rich liquor from the bottom of the absorber to the still; This s latter means includes a transfer chamber intermediate the absorber and the still and a valve arrangement whereby the chamber is selectively connected to the absorber or to the still.

Referring ,more particularly toe. specific sys I i0 tem schematically or diagrammatically illustrated in Figure 1, the still I is adapted to contain a mixture of water and ammonia. A flue ii is provided within the still and heat delivered thereto by the combustion of gas or some other Iii fuel delivered by the burner i2; An analyzer tower II, in the form of along cylindrical tubins enclosing the flue ll, rises from the upper part of the still, which is a vertical cylindrical vessel. Both the analyzer tower and the still are provided with baiile plates, as I4 and il, these plates serving to stratify the liquid in the still and to improve the eiliciency of the apparatus.

Rich ammonia vapors boiled off the liquor in the still pass upwardly through the analyzer tower it and then through the pipe connection ii to the rectifier ii, a finned inclined tube at the top of the system. From there the ammonia vapors, any entrained water vapor having been removed bythe rectifier, pass down through the I connection VI. to a condenser I! at the lower end of the apparatus. This condenser comprises one or-more loops of piping, finned to increase the heat radiation. The ammonia vapor is here condensed into liquid ammonia, and then elevated by the vapor pressure behind it through th connection 2|, a valve unit here indicated in general as 2!, and the connection 22 to the receiver 23.

The amount of ammonia boiled or! and lique- 10 fied is a function of the concentration of the liquor in the still and of the amount of heat supplied to it, so that if the concentration of liquor is kept relatively constant the rate of delivery oi. liquid ammonia to the receiver". will '45 be practically a direct function of the amount of heat supplied to the still. The amount of fueldelivered to the burner i2, and thus the amount of heat supplied and the rate of delivery of liquid ammonia to the receiver, can be regulated 'inany desired manner, as by a valve (not here shown) actuated in conventional mannerby a thermostat in the cooling chamber of the refrlserator.

Liquid ammonia passes iromthe receiver It condenser: an absorber in whichthe gas from II to the dry evaporator 24, preferably comprisingcontrol arrangement is such that, as more liquid ammonia is delivered to the receiver, flow from the receiver to the evaporator is increased to maintain the level of the liquid in-the receiver within certain desired limits.

Absorbing apparatus is provided in the form of an upper chamber or vessel 25 having an outlet pipe=26 at the bottom thereof leading to a liquid jacket 21 around a transfer chamber 28, and a fiow path from the jacket down through the pipe 29, the finned absorber cooling coil 30, and the upwardly extending pipe or leg 3|, this leg terminating in the absorber at a point slightly above the level of absorption liquid therein. This arrangement provides a cooling loop, liquid from the bottom of the absorber vessel 25 passing down through the jacket 21 and the pipe 29 to the cool,- ing coil 30, then returning through the pipe 3 the circulation being maintained when the refrigeration system is in operation by vapor admitted to this pipe 3|. The expanded ammonia vapor from the evaporator 24 passes down through the pipe 32 and loops around at the bottom toadmit the vapor to the rising leg 3| of the absorber cooling loop, this providing the liquid lift necessary to insure circulation. Inasmuch as the liquid in this rising leg is at all times the weakest liquor in the absorber,

' described, starting with the pipe 44, into the still.

and cooled by its passage through the absorber cooling coil 30, all absorption normally takes place in the pipe 3|, the enriched liquor flowing out of the top of this pipe. liquid in the absorber vessel 25 is maintained by a valve 33 controlling delivery of weak liquor from the still, this valve being actuated by a float 34. A-pipe 35 leads from the lower end of the still (where the liquor is weakest because of the stratification effected by the baflies l5) through a heat exchanger 36 and then on up to open into the absorber. The pressure in the still or generator ID at all times tends to drive liquid up this pipe 35, and its admission to the absorber is controlled by the float valve 33, so that any removal of liquor from the absorber causes an immediate replacement of its contents.

The means for returning rich liquor from the absorber to the still, necessary because this liquor must be returned despite the fact that the evaporator and absorber operate at low pressure and the still operates at high pressure, comprises as its principal parts thetransfer chamber 28 and v the valve unit.2 A fiow connection from the ab- The desired level of Whenthe movable valve means is moved to its other setting the transfer chamber is disconnected from the still by blocking the connection between'the pipes 4| and 42 and between the pipes '43 and 44. A very fine weak liquor bleeder orifice or passageway, here indicated as 48, delivers weak liquor under still pressure from the tub 35 to the top of the transfer chamber, and as soon as this chamber is disconnected from the still this weak liquor begins to absorb the high pressure vapor in the transfer chamber. This absorption progresses veryrapidly to the point where the transfer chamber pressure drops below the pressure in the absorber, whereupon the check valve 40 opens and the transfer chamber refills with rich liquor from the absorber. As this takes place the level of the liquid in the absorber is maintained by opening of the valve 33 by the float 34, as mentioned heretofore. As soon as the transfer chamber fills up solidly with liquid the weak liquor bleeder 48 raises its pressure to that in the still, so that only for the brief period necessary to refill the transfer chamber is there a complete pressure differential across the valve means in the valve unit 2|.

Actuation of the valve means in the valve unit 2| is accomplished by the thermostat bulb previously mentioned, located in the still I0 below the normal level, of liquid therein, but surrounded by the jacket 45. This thermostat bulb is connected by a liquid actuating leg 49 to a chamber in the bottom of the valve unit 2|. This chamber is divided into two parts by a sylphon bellows or similar arrangement, and still pressure is present in the upper part of the chamber, above the sorber to the transfer chamber is provided from the tube 3|, out through the short. open-ended cross tube v3| connecting therewith, then through the jacket 38, the pipe 39, and the check valve 40 intothe transfer chamber. When the movable valve means in the valve unit 2| is set in a cer-- tain position the transfer chamber is connected to the still II) by connecting the pipe 4| leading from the high pressure vapor line H? to the pipe 42 opening into the top of the transfer chamber; and by connecting the pipe 43 leading out of the bottomof the transfer chamber to the pipe 44. This latter pipe passes through the heat exchanger 36, through a jacket 45 around a thermostat bulb 46, and through the pipe 41 to open into the analyzer tower I3. In this setting of the valve means high pressure vapor admitted to the top of the transfer chamber equalizes its pressure with that in the still, so that liquid in the transbellows, at all times by reason of the fact that the pipe 44 opens into this chamber; and this pressure is balanced against another force, in this case the force of liquid delivered by the actuating leg 49 as a result of pressure generated in the thermostat bulb 46. As may be best seen in Figures 3 to 5, the valve unit includes snap action mechanism here identified in general as 50, so that when the still pressure exceeds the thermostat liquid pressure force the movable member 5| is in lower position, as shown in the drawings; and when the liquid thermostat force sufficiently exceeds still pressure the member 5| is moved to upper position. The thermostat bulb 46 is preferably filled with a' predetermined concentration of the refrigerant and absorbent used, as water and ammonia, so that the pressure in the thermostat rises rapidly whenever the concentration of liquor in the still drops below that in the bulb.

When the transfer chamber is connected to the still relatively cool liquid flowing back to the still, by passing through the'jacket 45 around the bulb 46, cools the bulb fairly rapidly and causes the thermostat bulb pressure to drop below still pressure sooner than would otherwise be the case.

Referring now more particularly to Figures 4 and 5, it will be seen that in the normal position of the valve member 52, as shown, connection between the pipes 4| and 42 is blocked, as is also connection between the pipe 43 and the chamber fer chamber drains down through the path just 76 tween the pipes 4| and 42 (see Figure 4); the

orifice 55 is covered to block connection between the pipes 20 and 22 (see Figure 5) and the orifice 51 is uncovered by the bottom of the valve-member 52 to permit liquid from the pipe 43, tq fiow into the upper part of the chamber within-the cause variations in heat exchange with the contents of the capillary tube 60, which in turn causes variation in the rate of movemeiit of refrigerant therethrough. The arrangement is such that the rate of movement of refrigerant through the capillary 80 is' at least partially a function of the rate of delivery of liquid refrigerant to the receiver 23. If the coiled portion of the capillary is completely submerged the refrigerant will pass through the capillary tube substantially entirely in liquid state, at a considerable rate of flow; whereas if the level of liquid in the receiver drops there will be a heat exchange between the exposed part of the capillary and the vapor at condensertemperature and pressure in the upper part of the receiver 23, causing vaporization of some of the liquid in the capillary tube and consequent retarding of the flow of refrigerant therethrough. This-particular feature of my refrigerant flow control arrangementforms the subject matter of my co-pending application Serial No. 361,629, filed October 17, 1940, and it will not, therefore, be further described.

, While the continuous absorption refrigeration system shown schematically in Figure 1 and dethere is no diiilcultyqin this regard, but it is highly desirable to avoid another set of moving parts, and particularly an expansion valve which frequently opens only partially and causes wire drawing and undesired erosion of the valve seat. For this reason it is preferable to use a capillary tube to provide the desired restriction to fiow from the high pressure condenser to the low pressure evaporator. V

The use of a capillary 'as the restrictor, however, presented an unexpected and unobvious dimculty in that it provided a continuous bleeding ofi of pressure from the high pressure side of the system and, when in a particular combination of circumstances, caused the still pressure to drop faster than the thermostat bulb pressure upon transfer action, so that the valves failed to stop transfer action before the chamber emptied itself, occasionally causing the system to shut down and fail to function.

Referring now more particularly to the charts of Figures 6 and 7, it will be noted that the still or generator pressure chart has had various points identified by a T to indicate when transfer took place in a domestic absorption refrigerator machine embodying all of the previously described structure except valve means in series with'the capillary. On the initial declining slope of the curve it will be understood that the evaporator temperature was low enough that the thermostat in the food chamber had the burner beneath the still turned down to its lowest, a mere pilot flame. At about the bottom'of the curve, after about fifteen minutes of run, it will be noted that the evaporator temperature has risen to scribed in general hereabove contains a number of inventions and improvements, this present application is directed to means for controlling delivery of refrigerant from the condenser in the high pressure side of the system to the evaporator in the low pressure side, where a valve is used in series'with a capillary tube. Other improvements in the system are the subject matter of my earlier filed joint and several co-pending applications, more'particularly applications Serial NO. 296,995, filed September 28, 1939, Serial No.

298,110, filed October 5, 1939, Serial No. 326,292, filed March 27, 1940, Serial No. 314,704, filed January 19, 1940, Serial No. 319,541, filed February 1'7, 1940, Serial No. 352,328, filed August 12, 1940,

Serial No. 388,155, filed April 11, 1941, and Serial 'No. 394,031, filed May 17, 1941. I

Control of transfer action by balancing still pressure against the force generated by a thermoabout seven degrees, and this is sufficient to cause the burner to be turned up to a light flame. The evaporator temperature still rising, the burner shortly; thereafter is turned up to medium and then to full flame, so that the still pressure shown on the first chart begins to rise rapidly. Under such circumstances, despite the dumping of rela-' tively cool liquor into the still upon the transfer action, the still pressure rises (even though not quite so sharply) upon each of thesucceeding transfer operations at about 28 minutes and 38 i minutes. By this time, however, the evaporator temperature has begun to drop and the burner is turned down through medium to pilot, so, that from forty-five minutes on the still pressure drops sharply. Under these conditions it will be noted thatwhen a transfer action -is initiated at about fifty-seven minutes the still pressure is [dropping rapidly, and it is under conditions such as these that the still pressure sometimes out- '00 stat exposed to the temperature of liquor in the still is very desirable in a. refrigeration system of the type here disclosed, since it provides automatic compensation for a number of variables which would otherwise vupset the system, maintaining proper quantities and concentrations of liquor in various parts of the system despite varying roomtemperatures, food compartment loads, and the like, as was brought out more fully in my above-mentioned application Serial No. 296,995. In order to keep the refrigerator from shutting down upon a transfer operation the valves mustbe reversed before the transfer chamber has completely emptied itself of liquid, preferably when there is still one-quarter or oneruns the drop in thermostat bulb pressure; and if this occurs the valves fail to reverse their positions and the system may shut down.

While I have now discovered this to be the reason for occasional failureof the'system, it was not obvious and required a long period of research and checking before I did discover the difiiculty and solve .the problem of overcoming it,

I by putting in serieswith the capillary tube a valve which is shut while the transfer chamber is emptying to' the still, being open at other times.

Turning now to Figures 8 and 9, illustrating.

generator pressures and evaporator temperatures in apparatus wherein the connection from the condenser to the capillary tube is through the third of the contents remaining in the chamber. When float-actuated expansion valves are used stant, at the time of transfer action. Calling attention to the transfer actions taking place on declining portions of thestill pressure curves, at fourteen minutes, twenty-one minutes, fifty minutes and sixty minutes, it will be noticed that there is a rise in still pressure incident to each transfer operation. Moreover, although it ddes not show on these charts, the arrangement tends to prevent wide swings in the burner from pilot to full, there being more periods of light and medium operation tending to maintain a smooth and more stable action of the system.

While I haveshown and described certain embodiments of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims.

I claim:

1. Apparatus of the character described for controlling delivery of refrigerant from a high pressure portion to a low pressure portion of a continuous. absorption refrigeration system incorporating means for periodically returning liquor from the low pressure portion to the high pressure portion and wherein the high pressure portion includes a.still, including: a capillary tube element designed to receive the entire pressure differential in the system; a valve element including a valve member adapted to be moved to open or closed positionand so constructed as to always remaineither in fully open orfully closed position, said elements being parts of a flow path connecting-the high and low pressure portions and all of the refrigerant flowing through said path passing through both of said elements; andmeans for moving said valve member, said means being responsive to a condition in the still.

2. Apparatus of the character describedfor controlling delivery of refrigerant fro-m a high pressure portion to a low pressure portion of a continuou absorption refrigeration system incorporating means for periodically returning liquor from the low pressureportion to the high pressure portion, including: a capillary tube element; a valve element including a valve member adapted to be moved to open or closed position, said elements being parts of a flow path connecting the high and low pressure portions and all of I the refrigerant flowing through said path passing through both of said elements; and means for moving said valve member, said means being responsive to the concentration of refrigerant in a part of the high pressure portion.

3. A continuous absorption refrigeration system of the character described, including: a still; a condenser, the still and condenser being adapted to operate at high pressure; an evaporator; an absorber, the evaporator and absorber being adapted to operate at low pressure; transfer means for periodically returning liquor from the absorber to the still; means connecting the condenser and evaporator, said means'including a capillary tube and a .valve; and means responsive to a condition in the system for opening and closing saidvalve, the operation of the valve being correlated with that of the transfer means.

4. A continuous. absorption refrigeration system of the character described, including: a still;

a condenser, the still and condenser being adapted to ,operate at high pressure; an evaporator; an absorber, the evaporator and absorber being adapted to operate at low pressure; transfer means for periodically returning liquor from the absorber to the still; means connecting the condenser-and evaporator, said means including a capillary tube and a valve; and actuating means for effecting operation of the transfer means and the valve, the arrangement being such that the valve is closed when the transfer means is returning liquor to the still.

5. Apparatus of the character claimed in claim 3, wherein the actuating means is responsive to still pressure and another condition in the system.

6. A continuous absorption refrigeration system of the character described, including: a still;

a condenser, the still and condenser being adapted to operate at high pressure; an evaporator; an absorber, the evaporator and absorber being adapted to operate at low pressure; transfer means for periodically returning liquor from the absorber to the still; means connecting the condenser and evaporator, said means including a capillary tube and a valve; and actuating means responsive to A the difference between still pressur and another force, the actuating means effecting operation of the transfer means and the valve and the .ar-

, rangement being such that liquor is moved from the transfer means to the still and said valve is closed when said force excee'ds still pressure and movement of liquor to the still is terminated and said valve is opened when still pressure exceeds said force.

"I. A continuous absorption refrigeration system of the character described, including: a still; a condenser, the still and condenser being adapted .to operate at high pressure; anevaporator; an ab sorber, the evaporator and absorber being adapted to operate at low pressure; a transfer chamber; a connection between the condenser and the evaporator including a capillary tube; a valve unit having movable valve means adapted in one position to connect the transfer chamber to the absorber and complete the connection between the condenser and theevaporator, and in another posttion to connect the transfer chamber to the still high pressure portion includes a still, including: a

capillary tube element; a valve element including a valve member adapted to be moved to open or closed position, said elements being parts oi a flow path connecting the high and low pressure portions and allof the refrigerant flowing through said path passing through both of said elements; and means for moving said valve member, said means being responsive to a condition in the still.

JOSEPH N. aorn. 

